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Blighted Ovum - Symptoms & Treatment

A pregnancy where the fetus does not develop properly is termed a blighted ovum. The fetus may fail to develop at all. Strange as it may seem, a fetus is not an essential part of an early pregnancy although it is appreciated that the reason for the pregnancy is the production of a fetus. Occasionally, the mass of cells in the center of the pregnancy that is destined to differentiate and develop into the fetus fails completely to get going. The whole pregnancy starts to develop normally; the chorionic villi grow on the outer side of the blastocyst and they implant in the wall of the uterus; the chorionic villi produce gonadotrophin, which stimulates the pituitary to release luteinizing hormone, which in turn provokes the corpus luteum in the ovary to produce large amounts of progesterone. Thus pregnancy is established.

At about this stage a group of cells known as the inner cell mass normally start dividing and differentiating into the different organs of the baby, but the presence of a developing fetus is not essential for the early part of pregnancy. At about the 6th week, however, the fetus should be developing its circulation and it is shortly after this, at about the 8th week of pregnancy, that the first signs that all is not well may appear since the chorionic villi must establish a circulation with the fetus so that they can form the placenta.

There may be a small amount of bleeding and, as a result of a very gradual reduction in hormone levels, the woman may be aware of a slight reduction in the symptoms of pregnancy. If a circulation between the fetus and the chorionic villi is not established by about the 10th week of pregnancy, continuous or intermittent bleeding may begin, and will be followed eventually by pain and complete abortion of the pregnancy from the cavity of the uterus.

Such a pregnancy contains a small amniotic sac but no fetus within its cavity. The exact reason for a blighted ovum is not known but it is generally considered to be caused by fertilization of a normal ovum by an abnormal sperm. It is impossible to prove this theory but in the majority of instances - where a blighted ovum is known' to have occurred, the husband's seminal count is usually deficient and contains more abnormal sperms than usual.

It is not known exactly how many abortions are due to blighted ova. It is however a commonly accepted view that approximately 1 in 5 of all human pregnancies are grossly abnormal and therefore miscarry spontaneously at about the time of the first period or they are blighted ova and miscarry at about the 8th or 10th week. Some authorities consider that blighted ova constitute 1 in 10 of all human pregnancies.

Diagnosis of Blighted Ovum

Blighted ovum can be diagnosed as early as the 6th week by ultrasonic scan because the early developing fetus will not be visible. By the 7th week the ultrasonic scan will fail. If the theories about a blighted ovum are correct, then once it has been diagnosed, the father should be examined and any abnormality in his seminal analysis corrected. However, it is an unfortunate fact that some couples are destined to produce more than their fair share of blighted ova when no abnormality can be found in either parmer. In such instances there is no constructive treatment to prevent a recurrence in a subsequent pregnancy. Only rather thankless reassurance can be given that sooner or later a normal pregnancy is bound to occur and that, when it does, it will continue normally into the production of a normal infant.